Before discussing about IES LM-80, I would like to introduce two concepts: life of lamp vs life LEDs.

1. Life of Lamp

When talking about life of lamp, we mean the operation time of lamp(s). For one piece of lamp, while most light sources burn out and the lamp has ended its life. That is operational failure.Typically, lamp life is rated at 50% failure rate.

2. Life of LEDs

Life of LEDs refer to the useful light output, which is referred to lumen maintenance.

Definition:

IES LM-80 is one approved method that measure lumen loss SSL light sources, arrays and module. Note that LM-80 measurement do not cover measurement of luminaires and does not define methods for life estimation.

Test Data:

Test report basics cover the following:

---Description of Sources tested

---Ambient conditions (Airflow, temperature, RH etc)

---Case Test point temperature

---Electrical conditions

---Lumen maintenance data

---Observation of failures

---Chromaticity shift over time

---LED monitoring interval

Test Conditions&Procedure

1. Ambient Conditions

Case Temperature measured and maintained

Case Temperature measurement point

Airflow minimized

Operating orientation & space

2. Electrical Setting

Voltage and Current (AC or DC levels)

Voltage waveform (harmonic distortion <3%)

Current regulation

3. Temperatures

4. Testing Intervals

---6000 hours min testing period, 10K preferred

--- Minimum at least every 1000 hours

IES TM-21

Definition:

TM-21 is a technical memorandum being developed by an Illuminating Engineering Society (IES).

It is currently in the IES vote/comment stage and therefore, may change before final publication.

It is one separate estimation method to test long term luminance maintenance, which is one important supplement for LM-80.

Scope:

---Adopted by organizations/programs as documentation of performance

---Program may define who does calculations( lab, manufacturer or other)

---TM-21 may be requested as part of LM-80 test

---Test lab will need to develop calculation sheet

Notice: TM-21 is under development. Here we do not make further discussion about it.